A . Introduction
1- The objective of classifying laser hazards is to provide the necessary warnings for laser users (by identifying the hazards associated with each level of radiation) by appropriate instructions and symbols. It will also be the basis for defining control and medical measures.
2. The produced lasers must be classified by the manufacturer and the markings and warnings must be installed on it. It should be noted that the laser classification may change if something changes to the laser system.
All international standards divide lasers into 4 classes in terms of damage that can be injected into the skin.
a. Class I: Under normal conditions, work can not damage the eyes, these lasers are usually closed lasers and their radiation is not sent to the environment. (Usually lasers with a power of 0.4 micro watts per visible wavelength). The users of these lasers do not threaten the risks of laser light, and do not need to perform control measures, but they need to take control measures when operating these lasers. Many of the lasers in this category have plenty of lasers that are placed in boxes or protective enclosures. Therefore, control measures should be taken when entering these rooms or opening the shields.
b. Class I.A: A group of low-power lasers that are not made for visual purposes (such as supermarket barcode lasers) fall into this category. The upper limit of this class of lasers is 4 milliwatts. These types of lasers are designed to increase the amount of energy that they deliver during 1000 seconds from class I lasers.
c. Class II: Low-power laser lasers that can withstand I-class lasers. But their radiant power does not exceed 1 milliwatts. These lasers do not harm the eye unless someone deliberately stares at them. Otherwise, the normal response of the eye to visible light and blink will protect the eye against the instant light of these lasers.
d Class IIIA: lasers whose output power is between 1 mW and 5 mW. These lasers usually do not cause serious damage unless the person stares at their light or their light can be seen with light concentrating devices like a lens.
Note: There is a difference between warning legs that do not exceed 2.5mW / cm2 on laser lasers (Warning Signs or Warning Signs) and Class IIIA lasers at a rate of 2.5mW / cm2 fdajv hsj (logo or sign of danger) has it .
e. Class IIIB: Continuous lasers whose output power is between 5 and 500 millwatts, or pulsed lasers whose energy is less than 0.125 jules in 0.25 seconds (the time required to blink human). Class 3b lasers are hazardous to the eye, and looking at their direct beam or mirror reflections of their beams can seriously damage their eyes. These lasers do not pose a risk of fire, and the reflections caused by the dispersion levels of these lasers are generally not dangerous. Certain control measures are required for these lasers.
f Class IV: Powerful lasers (Continuous: 500 MW, 10 J / cm2 pulses or dispersion thresholds) are continuous lasers with output power greater than 500 mW, or pulsed lasers whose radiant energy is greater in 0.25 seconds From 0.125 Jules. These lasers are very dangerous, their direct beam or mirror reflections, and even their diffuse reflections, are a serious danger to the eye. The rays of these lasers can also damage the skin or cause fires.